The graphic arts industry is confronted with the problem of delivering printed sheets for signatures to a gatherer which collects the various sheets in the usual manner of forming a magazine, book, or the like. In that gathering function, the industry employs mechanically operated sheet feeders which pass the various sheets to a gatherer moving past each of several sheet feeders to pick up the sheet or signature from each feeder and thereby form the final signature or magazine or the like. In that process and with that apparatus, the mechanically operating sheet feeders must be supplied with bundles of sheets so that the process can be continuous and extensive and of a nonstop nature. In that regard, U.S. Pat. No. 3,416,679 shows a sheet feeder which receives a bundle of sheets and moves the bundle upwardly to where the top sheet is removed from the bundle and is placed onto the gatherer, and the process is repeated in a plurality of side-by-side sheet feeders and the top sheets are continuously removed from the bundles and placed onto the gatherers to form the final signatures or magazines or the like. An operator is required to supply a fresh bundle to each of the sheet feeders and that requires his constant attention and effort in order to keep the sheet feeder supplied with the bundles for feeding to the gatherer.
The present invention improves upon prior art by eliminating the manual labor required in supplying bundles to the sheet feeders, and it also insures that the sheet feeders will always be in full supply of their respective bundles, and the entire method and system of this invention is automated.
To accomplish the automation mentioned, an overhead crane is employed and it includes a type of fluid-actuated cylinder such as that shown in U.S. Pat. No. 3,820,446, for example.That is, the present invention utilizes a crane which responds to the condition of a minimal amount of signatures in any one signature feeder, and the crane then moves to a supply of bundles of sheets and picks up one of the bundles and deposits it on that particular sheet feeder requiring same. The crane thus utilizes a fluid-actuated cylinder which can compress the bundle at its opposite ends to pick up the bundle and transport the bundle and then lower the bundle into the sheet feeder, all in an automated arrangement.
Further, the present invention provides both a method and apparatus for removing the binding and the end boards from the bundle when the bundle is placed into the sheet feeder.
In the aforementioned arrangement with the present invention, there is no requirement for any manual labor, and the entire method and apparatus are fully automated, and thus the process of supplying the sheets is reliable and continuous in a high production achievement.
Another object and advantage of this invention is to provide a method and apparatus of sheet feeding and wherein valuable floor space is conserved in that only a minimal amount of floor space is required.
The aforementioned advantages and objectives are achieved in production where, for instance, a 300 page magazine is to be produced at the rate of 300 per minute. This requires that somewhere on the production line a bundle 40 inches long is required within every 18 seconds. The method and apparatus of this invention can automatically fulfill those high speed requirements without the need for manual labor and with only a minimum of apparatus and a minimum of valuable plant floor space being required.